There is a public menace on the streets of Perth, Australia: two motorized picnic tables. Police are looking for the drivers of the, erm, vehicles, which were seen cruising down the West Coast Highway, complete with passenger casually sitting on the tables having a drink. It looks like the two picnic tables are being driven by a centrally mounted lawnmower motor and are controlled from one of the seats. The police are interested because it is illegal to drive something on the public road in Australia that isn’t properly licensed. I’ll bet that his insurance probably doesn’t cover taking it out for a spin on the highway, either. The accompanying TV news report does not identify the person responsible, but they claim have spoken to the builder, who says that the two tables can manage up to 50 miles per hour. They claim that he is even working on an upgraded model that includes a built-in barbecue, which could bring a whole new meaning to the term drive-thru.
[RimstarOrg] has posted an awesome writeup on his Hero’s steam engine . Hero’s engine is a Greek design from the first century and is the earliest known steam engine. It’s amazing to think he developed the engine seventeen centuries before the industrial revolution, and yet it was largely ignored. While you can find more faithful replicas, of this landmark machine [RimstarOrg]’s rig can’t be beaten for simplicity and he does a great job of explaining the principal of operation and construction.
Using a soda can filled with water and a propane torch [RimstarOrg] was able to get the can to rotate rapidly by ejecting steam from two holes in the side of the can. A fishing swivel is used to provide a pivoting joint and allow the can to rotate freely.
While we’ve covered steam engines before, we loved this simple design, and can’t wait to see what [RimStarOrg] comes up with next.
There are plans for open hardware farming equipment that can be brought to third world countries to relieve the beasts of burden and increase the production of fields. Want an open source car? You can 3D print one. Just about anything you can strap a motor to has been replicated in open hardware; all you need to do is buy a motor and bolt it on.
But what about the motors themselves? For his entry to The Hackaday Prize, [Shane] is designing an open source engine. It’s small, it’s a two-stroke, and it’s diesel, but it’s completely open hardware; a great enabling project for all the open source dirt bikes and microcombines.
The design of [Shane]’s engine is based on the Junkers Jumo 205; a weird engine that had opposing pistons in one cylinder. This allows the engine to have variable compression, allowing for a wide variety of fuels to be used. If you have kerosene, that’ll work with this engine. French fry oil will as well. It’s exactly what you need for an engine that could be used for anything.
The 2015 Hackaday Prize is sponsored by:
As a beginner’s step towards the famous Top Gear V8 coffee table, [English Tea] converted a small single cylinder engine into a desk lamp that uses the mechanical actuation of the piston to turn on and off. No able-bodied engines were harmed in the making of this hack as this one was already a corpse — perfect for [Mr. Tea] to prop up and display in his home.
Regrettably lacking a lightsaber, he settled for 30 minutes on a hacksaw to split the cylinder followed by some sandblasting to clean all the rust, paint, and gunk off all the internals. Once it was clean he repainted it himself. Between paint and clearcoats, he figured he added 20 layers onto the metal.
Next he created some wood sections and wet-formed leather over them which he later dyed black. Caring less about a new Walmart lamp than the motor, he vivisected it for its electrical components and wired it up.
Without a crank on the shaft it looks a bit awkward to twist the lamp on or off, but, only enough pressure is needed to poke a latching
momentary pushbutton and it seems to work just fine. For any readers looking to make their own, dead compressors and gas power tools are fairly common and nearly free at the junkyard. Engine-based projects can be intimidating to start if you need a working engine again at the end. Becoming familiar with them on a project like this where you are mostly only using the engine as a building material is an easy way to get your foot in the door.
See the video after the break of the piston bumping the light on and off.
Anyone can strap a two-stroke engine on a bicycle to create a moped. But [robinhooodvsyou] has created something infinitely more awesome. He’s built an inverted open crank engine on a 10 speed bicycle. (YouTube link) As the name implies, the engine has no crankcase. The crankshaft, camshaft, and just about everything not in the combustion chamber hangs out in the open where it can be seen and appreciated.
[robinhooodvsyou] started with an air-cooled Volkswagen cylinder. He filled the jug with a piston from a diesel car. Camshaft, flywheel, valves, and magneto are courtesy of an old Briggs and Stratton engine. The cylinder head, crankshaft, pushrods, and the engine frame itself are all homemade.
Being an open crank engine, lubrication is an issue. The crankshaft’s ball bearing is lubricated by some thick oil in a gravity fed cup. Even though the engine is a four-stroke,[robinhooodvsyou] adds some oil to the gas to keep the rings happy. The camshaft and connecting rod use Babbit bearings. While they don’t have an automatic oiling system, they do look pretty well lubricated in the video.
Starting the engine is a breeze. [robinhooodvsyou] created a lever which holds the exhaust valve open. This acts as a compression release. He also has a lever which lifts the entire engine and friction drive off the rear wheel. All one has to do is pedal up to cruising speed, engage the friction drive, then disengage the compression release.
We seriously love this hack. Sure, it’s not a practical vehicle, but it works – and from the looks of the video, it works rather well. The unmuffled pops of that low 4:1 compression engine reminds us of old stationary engines. The only thing we can think to add to [robinhooodvsyou’s] creation is a good set of brakes!
Sometimes we forget how many things we can do with a simple oscilloscope. In this video [Ben] uses one that Tektronix lent him to measure his DeLorean engine RPM. By checking the car main ~12V voltage one may notice that the voltage spikes occurring are directly related to the engine speed, as they are created by the inductive kicks from the ignition coils. Obviously the multiplication you have to do to get the RPMs from the number of spikes per second depends on your engine configuration (flat 4, v6…).
The method that [Ben] used was to search for high amplitude spikes on the (AC coupled) car 12V Fast Fourier Transform (FFT) to get a reliable measurement given the many electrical noise sources present in his car. At the end of his video, he however mentioned that it could still be possible to get a good measurement with a simple voltage comparator and a high enough voltage reference.
A few months ago we mentioned [Keith]’s first project in the works, a 1/4 scale V8 engine. Today, we are amazed to see that his engine is finished and running really smoothly. What is even more impressive is that the entire project has been completed on manual mills and lathes. The thread on the Home Model Engine Machinist forum contains his build log in which he details how all the different parts were made. The engine has an electric starter, uses a fuel injection system and [Keith] even made his own injection molds for several plastic parts. The ECU is based on the Megasquirt-II, we guess it must have taken [Keith] many tries before correctly setting its parameters. A video of the engine in action can be viewed after the break.
You can find our previous coverage of this project as well as other miniature engines on this feature from last April.